In the past, various types of case handling machines have been developed. Case handling machines include machines for assembling or erecting cases, machines for sealing cases and machines for placing inserts in cases, plus various combinations thereof. For example, some case handling machines both assemble or erect cases and, then, partially seal the erected cases. Other case handling machines merely seal cases. In some instances, sealing is accomplished using an adhesively coated tape. In other instances, an adhesive is applied directly to the major and/or minor flaps of the case to be sealed.
A tray is a specialized case that is low and flat when assembled, and usually formed such that major and minor flaps to be attached to one another are located on opposite sides of the case, rather than at the top and/or bottom of the case. Trays are often used to house a plurality of similar products, such as a case of beer or pop, several grapefruit or a plurality of ceramic objects, for examples. Trays can be open topped; or, include a top designed to be folded over and inserted with or without being sealed, after the item or items to be housed in the tray have been placed therein.
The present invention is directed to tray forming machines suitable for applying adhesive to the side major flaps of tray blanks, folding the glue bearing side major flaps over side minor flaps and causing the glue joined flaps to adhere to one another.
In the past, tray forming machines have been either entirely manually controlled or semi-automatically controlled. Manually controlled machines are undesirable because they are slow and labor intensive. While semi-automatically controlled machines are faster and, generally, decrease the amount of skilled labor needed, semi-automatically controlled machines have other disadvantages.
The major disadvantage of prior art semi-automatically controlled tray forming machines is the difficulty associated with changing the mode of operation of such machines. Mode of operation changes are required because tray sizes vary over a wide range. Mode of operation changes are also required because joint strength varies depending upon the size and weight of the product or item to be housed in the tray. Because different joint strength requirements exist, different trays have different glue amount requirements. In order to change the mode of operation of prior art semi-automatically controlled tray forming machines, various adjustments must be made by a skilled mechanic. Moreover, the mechanical control systems used in prior art machines (which include timing wheels and related mechanical devices) are subject to wear and, thus, frequent adjustment by a skilled mechanic. In addition to the cost attendant to the services of a skilled mechanic, the loss of machine time (e.g., machine downtime) attendant to such changes is greater than desirable. Machine downtime is undesirable for two reasons--the idle time of the machine operator; and, the idle time of employees filling the trays being formed by the machine. Thus, there is a need for a tray forming machine having a control system that is not subject to mechanical wear and whose mode of operation can be rapidly changed without requiring the services of a skilled mechanic.